An innovative water and ice detection system for monitoring road and runway surfaces

Detection of water and ice over road and runway surfaces is an important issue in improving traffic safety and reducing costs for the maintenance, especially during winter. A low cost capacitive sensor for the estimation of road and runway conditions is studied. An algorithm for the estimation of the state of road and runway surfaces (dry, wet, or icy) was developed based on experimental results, which indicated that the time derivative of the measured capacitance provided optimal information. Accuracy and reliability of the estimates provided by the sensor was assessed in laboratory conditions, placing more sensors in a climatic chamber in the same conditions and investigating the estimates of the state of the sensors and the timing of the identification of wet-icy or icy-wet transitions. Reliable estimates were obtained by all the sensors, with a dispersion of the transition times of the order of a few minutes.